Radio receivers are known and the use of noise blankers in receivers, such as frequency modulated (FM) broadcast receivers used in automobiles and the like is also known. Generally noise blankers are used to eliminate or mitigate the impact of noise, such as noise that may be generated by ignition systems and the like, on the resultant audio.
One way of assessing the impact of the noise is to apply a “standardized” noise source along with a variable level radio frequency signal without modulation to an input of a receiver and measure residual noise at the speakers as a function of the level of the radio frequency signal at the input. This measured residual noise is compared to the level of the signal at the speakers when a variable level modulated radio frequency is applied. It is desired that the residual noise level be as low as possible.
Often the noise blanker is implemented and operates on a demodulated signal and may be referred to as an audio blanker. Typically audio blankers inherently do some harm to audio quality or fidelity and thus should only operate when the harm done is offset by the noise mitigation. Thus the audio blanker will generally need to be enabled or controlled. Often a noise detector is used to detect noise and when detected enable the audio blanker. Known noise detectors tend to have falsing problems (false positive indications of noise or failure to detect actual noise) under various conditions, e.g., signal levels, noise characteristics, and the like.